EP 0 957 716 B1 discloses a vehicle seat with a backrest and a seat part, in which a lumbar support mechanism is installed in the backrest region, said lumbar support mechanism being composed of a flexible support member which is secured at its upper and lower ends and can be drawn together such that an arch forms for example in the lumbar spine region. As a result, a lumbar support is obtained which can be adjusted in the forward direction so as, by means of a convex deformation of the backrest in the lumbar spine region, to provide more or less support for the person depending on whether said person has a more or less pronounced hollow in the small of his back, in order to increase the seating comfort.
The deformation of such lumbar spine supports is preset by the person, and remains as such until the person readjusts it for example by actuating a hand-wheel, to which a Bowden cable is attached.
Such a support member has an expensive and complicated structure in so far as it requires a device for securing the support member, sliding elements, and also a plurality of support arms which extend horizontally and are connected to one another.
EP 1 082 233 B1 discloses an elastic arch element for backrests, which acts as a lordosis support. The arch element consists of an essentially sheet-like arching element part and of at least one panel with two free resilient ends which is fixedly connected to said arching element part over a small surface area, wherein, when said element part is arched, the panel serves as a support with respect to a backrest pad arranged thereon. The arching part is actuated independently of the current position of a seat part of the vehicle seat, and requires the separate actuation of actuating elements provided for this purpose.
EP 0 303 720 B1 discloses a vehicle seat with a backrest frame which is L-shaped in side view. One limb of the L-shaped backrest frame engages under a seat frame. In order to adjust the inclination of the backrest, the limb is guided by means of a pair of rails such that, during a forward movement of the seat frame, the free end of the other limb arranged in the backrest region moves in the opposite direction and downwards. In this way, a forward movement of the seat surface gives rise to automatic backward inclination of the backrest, but without thereby changing the shape of the backrest in the lumbar spine region.